(1) Field of the Invention
This invention relates to a dental X-ray film pack useful in X-ray photography upon dental diagnosis and/or treatment.
(2) Description of the Prior Art
X-ray pictures of teeth are usually taken in bright examination and treatment rooms. A dental X-ray film (hereinafter simply called "film") is therefore enclosed in a light-tight outer packaging member so that a dental X-ray film pack is formed. It is inserted to a desired position within a mouth, followed by irradiation of X-rays. After completion of exposure to X-rays, the dental X-ray film pack is taken out of the mouth. In a dark room or box, the outer packaging member is peeled and the film is taken out and is then subjected to development, fixing and water-washing treatments to obtain an X-ray image of teeth on the film. There are a variety of types among such dental X-ray film packs. The construction of one example of dental X-ray film packs will next be described with reference to FIGS. 1 through 3 of the accompanying drawings.
FIG. 1 is a top plan view of a conventional dental X-ray film pack. FIG. 2 is a cross-sectional view taken along line II--II of FIG. 1. FIG. 3 is another cross-sectional view taken along line III--III of FIG. 1. In each of the drawings, there are shown a film 1 and a light-tight opaque sheet 2 covering both sides of the film 1. As the light-tight sheet 2, an elongated black paper sheet having the same width as the film 1 may be used by way of example. The light-tight sheet 2 is folded back at folded-back portions 2a,2b and the folded-back end portion forms an overlapping portion 2c. As a result, both sides of the film 1 is shielded from light. Designated at numeral 3 is a reflective sheet interposed between the light-tight sheet 2 and the folded-back overlapping portion 2c of the light-tight sheet 2. The reflective sheet 3 is made, for example, of a thin metal foil such as lead foil. The light-tight sheet 2 and reflective sheet 3, in combination, form an inner packaging member.
Numeral 4 indicates an outer packaging member, within which the film 1, light-tight sheet 2 and reflective sheet 3 are enclosed. As the outer packaging member 4, may be used by way of example an elongated opaque sheet made of a synthetic resin, e.g., polyvinyl chloride, and having a width slightly broader than the width of the film 1. There are also shown folded-back portions 4a,4b of the outer packaging member 4, a folded-back section 4c extending further from the folded-back portion 4b, and a peeling tab 4d formed at a free end portion of the folded-back section 4c. The folded-back section 4c and peeling tab 4d, in combination, form a peeling piece. Along both sides 4e,4f of the outer packaging member 4, the upper and lower sheet sections of the outer packaging member 4 are heat-sealed as shown in FIG. 3. Numeral 5 indicates a weak adhesive layer adhering the folded-back section 4c and the underlying upper sheet section of the outer packaging member 4 by a weak adhesive force, whereby tee film 1 is enclosed light-tight within the outer packaging member 4. It should be noted that the thickness of each element of structure is shown on an extremely enlarged scale in FIGS. 2 and 3 and the overall thickness of the dental X-ray film pack is slightly greater than 1 mm as a matter of fact.
Upon taking an X-ray picture, the above dental X-ray film pack is inserted and fixed in a mouth with the side opposite to the side, in which the peeling tab 4d is formed, being maintained in contact with teeth as an object for the X-ray photography. X-rays are then irradiated through the teeth. The X-rays penetrate through the teeth and transmit through the outer packaging member 4 and light-tight sheet 2, so that the film 1 is exposed to the X-rays to form an X-ray image (latent image) of the teeth. Upon this X-ray photography, X-rays which may penetrate from the side of the peeling tab 4d by reflection and the like are reflected back by the reflective sheet 3 so as to avoid penetration of unnecessary X-rays to the film.
After completion of photography in the above-described manner, the dental X-ray film pack is taken out of the mouth and the film 1 is removed from the dental X-ray film pack in a dark room or box, followed by its development and fixing treatments.
In order to take out the film 1 from the dental X-ray film pack in the dark room or box after completion of the X-ray photography, the peeling tab 4d is first of all pulled in a direction indicated by an arrow 6 in FIG. 2 so as to peel off the tab 4d from the weak adhesive layer 5 . When the peeling tab 4d is pulled further in the direction of the arrow 6, the heat seal between the side edges 4e and 4f (the righthand side edge as viewed in FIG. 1) of the outer packaging member 4 is eventually separated. As a consequence, an opening is formed in the right of the outer packaging member 4. The reflective sheet 3, light-tight sheet 2 and film 1, which have been enclosed within the outer packaging member 4, are taken out through the opening and the reflective sheet 3 and light-tight sheet 2 are then removed to separate the film 1.
In the above-described procedure, it is however extremely irksome to remove the reflective sheet 3, light-tight sheet 2 and film 1 together from the outer packaging member 4 and then separate the film 1 alone from the reflective sheet 3 and light-tight sheet 2. This irksomeness is aggravated further, especially, when the above work is carried out by touch in a dark box.